Search results
Results from the WOW.Com Content Network
Values are primarily retrieved using the indexer (which throws an exception if the key does not exist) and the TryGetValue method, which has an output parameter for the sought value and a Boolean return-value indicating whether the key was found.
find the value (if any) that is bound to a given key. The argument to this operation is the key, and the value is returned from the operation. If no value is found, some lookup functions raise an exception, while others return a default value (such as zero, null, or a specific value passed to the constructor).
A hash table uses a hash function to compute an index, also called a hash code, into an array of buckets or slots, from which the desired value can be found. During lookup, the key is hashed and the resulting hash indicates where the corresponding value is stored. A map implemented by a hash table is called a hash map.
This entails modifying the used hash function to reflect the new key-space of the resized table. A concurrent growing algorithm is described by Maier et al. [1] Mega-KV [7] is a high performance key-value store system, where the cuckoo hashing is used and the KV indexing is
For example, key k could be the node ID and associated data could describe how to contact this node. This allows publication-of-presence information and often used in IM applications, etc. In the simplest case, ID is just a random number that is directly used as key k (so in a 160-bit DHT ID will be a 160-bit number, usually randomly chosen ...
The same technique can be used to map two-letter country codes like "us" or "za" to country names (26 2 = 676 table entries), 5-digit ZIP codes like 13083 to city names (100 000 entries), etc. Invalid data values (such as the country code "xx" or the ZIP code 00000) may be left undefined in the table or mapped to some appropriate "null" value.
An update that is supposed to change the key of an Entry (k1,v) to an Entry (k2,v) atomically would need to do a remove(k1) and then a put(k2, v), while an iteration might miss the entry or see it in two places. Retrievals return the value for a given key that reflects the latest previous completed update for that key. Thus there is a 'happens ...
Cuckoo hashing is a form of open addressing in which each non-empty cell of a hash table contains a key or key–value pair.A hash function is used to determine the location for each key, and its presence in the table (or the value associated with it) can be found by examining that cell of the table.